Desulfurization of oils



Oct. 5, 1948. B. L. EVERING ETAL DESULFURIZATION OF OILS 2 Sheng-sheet 1Filed May 19, 1945 Det. 5, 1948.

Filed May 19, 1945 FLSH DRUM EXTRA C TOR 2 Sheets-Sheet 2 EXTRA CTORFeed In v`enors. Bernard L. Ever-ing #rf/zur Lien James IVI. Page, Jr

Patented Oct. 5, 1948 UNITED STATES; PATENT .OFFICE DE SULFURIZATION OFOILS Bernard L. Evering', Chicago, Ill., Arthur P. Lien,

Hammond, Ind., and James M. Page, Jr., Chicago, Ill., assignors toStandard Oil Company, Chicago, Ill., a corporation of IndianaApplication May 19, 1945, serial No. 594,610

The present invention pertains to improvements in the refining ofnon-viscous hydrocarbon 4 Claims. (Cl. 196-31) oils and moreparticularly pertains to the desulextraction of petroleum oils with amixture 'of anhydrous liquid HF and BFa possesses the undesirablefeature in that any aromatics present in the stock extracted are alsoremoved as part of the extract. The removal of aromatics from variouspetroleum fractions may not be undesirable. but for the treatment ofcertain fractions, particularly the lighter fractions boiling within thenaphtha distillation. range and up to a maxlmum distillation temperatureat about atmospliericl pressure of about 450 F., it is highly desirableto retain in such fractions any aromatics which may be containedtherein.

It is an object of the present invention to provide a solvent extractionmethod of desulfurizing non-viscous petroleum fractions without the re-lmoval of substantial quantities of aromatics. An-

, about 50 volume percent, although for certain other object of theinventionis to provide an improved process of solvent extractingnon-viscous petroleum fractions with a solvent which is selective to theremoval of sulfur from such. fractions. Another object of the inventionis to provide an improved solvent extraction process forthe removal ofsulfur and sulfur-containing'constituents from petroleum-naphtha boilingwithin the motor fuel distillation range. Another object of theinvention is to provide an improved method for the desulfurization ofpetroleum naphthas. Still another object of the invention is to providean improved process for the removal of sulfur withoutthe removal ofsubstantial quantities of aromatics from petroleum naphthas. Otherobjects and advantages of the present invention will become apparentfrom the following description thereof read in conjunction with theaccompanying drawing in which Figure 1 is a flow `diagram of a preferredmethod of carrying out the present invention, and Figure 2 is a, owdiagram of a modiedmethod of treating the initial feed stock.

In accordance with the present invention the 'foregoing objects can beattained non-viscous petroleum oil fractions, such as naphthas and motorfuels, with a solvent consisting of anhydrous liquid hydrogen fluoride.The quantity of anhydrous liquid hydrogen fluoride employed should besufficient to give a diphasic separation, and can vary from about 10volume percent to about 100 volume percent or more and preferably fromabout 15 volume percent to types' of oils as little as 5 volume percentor less will givek a diphasic separation. Temperatures of from about 0F. to about 212.J F. and preferably from about 32 F. to about 100 can beemployed. However, if desired somewhat higher temperature, for exampletemperatures of about 400 F. can be used, in the manner hereinafterdescribed. A pressure suiiicient to maintain the solvent in the liquidphase is preferably maintained in the extraction chamber. A contact timeof from about one minute to about 120 min-` utes or more can beemployed, although a contactY time of from about 5 minutes to about 60minutes is usually suflicent.

A method for practising the present invention is illustrated by thefollowing example:

Referring to Figure 1, va sulfur-containing gasoline fraction having aninitial boiling point of about 215 F. and an end point of about 420 F.by A. S. T. M. distillation, is introduced through ,line I0 into thebottom portion of the extractor l II, while liquid anhydrous hydrogenfluoride is introduced into the upper portion of the extractorV througha line I2. The extractor II is suitably a 'packed column in whichanhydrous hydrogen fluoride and the sulfur-containing feed stock arecontacted countercurrently, although other suitable means of obtainingintimate contact can be employed. The extractor II is operated at 'atemperature within the range of fromabout 0 F. to about 212 F. andpreferably from about 32F.- to about 100 F., and under sufficientpressure to maintain the reactants in the .liquid phase. l l

A raffinate substantially free of sulfur or having a sulfur-contentsubstantially lower than that ,of` the feed stock, vis removed from theextractor II through a line I3 and introduced into a settler I4,Whereinany entrained HF or HF extract is settled out and returned through aline I5 to the extractor I I via line 58. The raillnate containingdissolved hydrogen fluoride inthe settler I4 is by extractin'g n uponthe stock being treated.

introduced through aline I6 and e. pump IBa into the bottom portion of astripper I1. Even when the overhead from the extractor II does notcontain entrained HF, it is advantageous to employ settler I4 tofunction as an accumulator and to protect against surges. Gases insettler I4 can be vented through a vent (not shown) or withdrawn throughlines I8, I9 and I2, and returned to the extractor II. If desired, theoverhead from the extractor II can be passed through lines I3 and I3a tothe stripper I1, thereby by-passing settler I4,

The ramnate product stream introduced into the stripper I1 is heated bysuitable means, such as by a heating coil 20, to remove hydrogenfluoride from the product. Stripper I1 is operated under pressure andtemperature conditions to assure the removal of substantially all of thehydrogen fluoride from the rafilnate product. These conditions-will varyover a wide range depending For example. when a gasoline fraction havingthe aforementioned distillation characteristics is employed as the feedstock, temperatures within the range of from about 200 F. to about 450F., and preferably from about 300 F. to about 400 F. and pressures fromabout'5 to about 150 pounds per square inch, and preferably from about25 to about 100 pounds per square inch are suitably employed. Hydrogenfluoride separated in the stripper I1 is removed overhead through a line2I and can be directed through line 22 to the hydrogen fluoride storagetank 23; or can be recycled through lines 24, 25, I9 and I2 to theextractor Il. hydrogen fluoride can be introduced into the systemthrough line 23a.

The bottoms from the stripper I1 comprising a substantially desulfurizedralnate product substantially free of hydrogen fluoride can normally beremoved from the stripper I1 through alline 26 and passed through aconventional bauxite tower 21, or other suitable system to insure theremoval of iluorides, such as hydrogen fluoride and alkyl fiuorideswhich may be contained in the desulfurized product from the stripper I1.The desulfurized product, substantially free of iluorides, is removedfrom the tower 21 through a line 28.

When a stock, such as furized contains butanes, an azeotrope with thehydrogen fluoride may be formed. To separate the components of theazeotrope the butane-hydrogen fluoride from stripper I'I through lines2l, 22, valved line 29 and a condenser 30 to a settler 3l which isoperated at as low a temperature as can beobtained with availablecooling water, preferably at a. temperature well below 100 F. Thecondensed azeotrope separates into a heavier hydrogen fluoride layerwhich is withdrawn through lines '32 and 22 to the hydrogen fluoridestorage tank 23. u The upper butane` layer is returned through pump 33and line 34 as reflux to the top of stripper I 1. Lighter gases and somepropane nay be vented from the settler 3l through a line 3 gasoline,being desul- The hydrogen fluoride extract from the extractor I I ispassed through a line v36 to a hydrogen fluoride recovery tower 31, thebottom temperature of which is maintained at a temperature between about100 F. to 150 F. by heating coil 38, to drive off the unbound hydrogenfluoride, The hydrogen fluoride from the tower- 31 is passed throughlines 39 and 4II through a condenser 4I to a receiver 42. If the extractfrom Makeup I azeotrope is passed overhead pounds along with theextractor II contains some low boiling hydrocarbon fractions, theoverhead from the tower 3l is first fractionated by suitable means (notshown) to fractionate the hydrogen fluoride from the low boilinghydrocarbons before the former is recycled to the hydrogen fluoridestorage tank 23. The bottom from the tower 31 is passed through a line43 to a second hydrogen fluoride recovery tower 44, provided withsuitable heating means,l such as a heating coil 45 to maintain a bottomtemperature therein of from about F. to about 500 F. to decompose thechemically bound hydrogen fluoride which is passed from tower 44 throughlines 46, 40 and condenser 4I to the receiver 42, while the extract,substantially free of hydrogen fluoride, but having a high sulfurcontent is removed from the tower 44 through a line 41.

Some'water enters the system through the feed stock and makeup hydrogenfluoride. To prevent this water from building up in the system, it isremoved by by-passing a portion of the recycled hydrogen fluoride fromtowers 31 and 44 through a line 48 to a hydrogen fluoride-waterazeotrope silver-lined distillation tower 49, provided with a suitableheating means 50 in the bottom portion thereof. Anhydrous hydrogenfluoride is removed overhead from the tower 49, through lines 5I and 40and condenser 4I to receiver 42, and aqueous hydrogen fluoride isremoved from the bottom of tower 49 through a line 52. A portion of theanhydrous hydrogen fluoride in receiver 42 is returned through line 53and pump 54 to the top of tower 49 to serve as reflux. The hy.. drogenfluoride in receiver 42 can be passed via pump 55 and a line 56 to thestorage tank 23.

A portion of the extract from extractor II may, if desired, be recycledto the extractor I I through lines 51 and 58. Itis to be understood thatwhile we have shown a single extractor in Figure 1, a plurality ofextractors may be used; also HF extract can be recycled to the sameextractor or to diuerent extractors.

In the foregoing example we have described extraction at a temperatureup to about 212 F. Under some conditions it may be desirable to carryout a conversion and/or an extraction at an elevated temperature aboveabout 212 F., for example about 300 F. to 400 F., followed by anextraction at a lower temperature, for example, about 0 F. to about 212F., preferably about 75 F. Thus, the sulfur-containing feed stock can becontacted with liquid anhydrous hydrogen uoride at the elevatedtemperature, say about'400 F. and the hydrogen sulfide, resulting fromthe conversion of some of the sulfur comany lighter hydrocarbons, aftercooling, is flashedoff. The resultant mixture of hydrogen fluoride andtreated product can then be cooled to the final extracting temperature,for example about '75 F., additional hydrogen iluoride added ifnecessary and the extraction process proceeding as above described. Ifdesired, a, diphasic separation can be made after contacting at theelevated temperature and cooling to the lower temperature, the extractlayer removed, additional hydrogen fluoride added and an extraction madeat a temperature of from about 0 F. to about 212 F., preferably about 75F. as above described. This combined conversionextraction processresults in a very effective desulfurlzation of the stock so treated.

This modied high temperature treatment of the initial feed stock can becarried out as follows: Referring to Figure 2 the feed stock, containingsulfur, and hydrogen fluoride are introduced into the extractor IIthrough lines I and I2 respectively, and the mixture hea-ted to atemperature above about 212 F., for example from about 300 F. to 400 F.The heated mixture from the extractor II is passed through line I3 andacooler I3b to a flash drum Ilia wherein hydrogen sulfide resulting fromthe conversion of the sulfur compounds in the feed stock, along withlight hydrocarbon, are hushed ofi through vent IIb. The mixture ofhydrogen fluoride and treated product in flash drum Ida is passedthrough line I5a and cooler I5b to extractor IIa and mixed withadditional hydrogen fluoride introduced through line |2a. A pressuresufficient to keep the hydrogen fluoride and hydrocarbon oil intheliquid phase is maintained within the extractor I Ia. The mixture ofhydrogen uoride and oil in extractor I Ia is allowed to separate intoa'. raffinate phase and an extract phase, and the raffinate withdrawnfrom the extractor IIa through line IIb passed to settler I4 (Figure 1)and thereafter processed as hereinbefore described in connection withFigure 1. The extract is withdrawn from the extractor IIa through line36a and introduced via line 36 to the hydrogen fluoride recovery towerNo. I (shown in Figure l) and thereafter processed as hereinbeforedescribed.

Alternatively, themixture of oil and hydrogen fluoride in extractor I Iamay be agitated without added hydrogen fluoride and then separated intoa railinate phase and extract phase. The rafll-A.

nate phase may then be withdrawn through line IIa and the extract phasethrough line 36a and .processed as above described. If desired, theextract in the extractor IIb may be withdrawn through line 36a,additional hydrogen fluoride introduced into the extractor IIa throughline I2a, the mixture agitated and -then settled to obtain a furtherrainate phase and extract phase which may then be withdrawn fromextractor I Ia and processed in themanner hereinbefore described.l

The ellectiveness of anhydrous liquid hydrogen fluoride as a solventextractant for the removal of sulfur from non-viscous hydrocarbon oilsis demonstrated by the data in Table I. These data Were obtained byextracting a heavy naphtha cut hydrogen fluoride and boron fluoride isclearly obtained by extracting at a temperature cf about 80 F. and withacontact time of about 60 minutes a heavy'naphtha having initialdistilla tion of about 218 F. and an end point of about 416 F. fromSlaughter crude, using as the solvent extractant anhydrous liquidhydrogen fluoride alone, and anhydrous liquid hydrogen fluoride incombinationv 'with boron fluoride. Run 1 was made by extracting theheavylnaphtha with a mixture of 400 cc. of hydrogen fluoride per literof naphtha and" 67 grams of boron fluoride per liter of naphtha whichvgave an initial boron iluoride pressure of pounds per square inch inthe extractor. Run 2 was made underidentical conditions as in Run 1except that the boron fluoride was omitted.

`TABLE II s Di Octane No. T v pcc. sp. HIL

Bu ko' HF BF Rallinatc Loss Wt.

Clear 3 cc. Percent ne l41.9 54.2 f 104 35. 6 604 7 15.1 116 40. 3 G1. 52. 3

Comparison of the specific dispersions of the feed stock and theraiiinate from Runs 1 and 2 show that with the hydrogen fluoride alonethe extraction of aromatics is substantially negligible, whereas withthe mixture of hydro-gen fluoride and boron fluoride a high degree ofaromatic extraction .took place The specific dispersion value indicatesthe degree of aromatlcity of the extracted naphtha. The specificdispersion value of 116 inthe feed'and in Run 2 indicates substantiallyno removal of aromatics from the feed stock, whereas the specificdispersion value of 104 for the raffinate in Run 1 indicates-asubstantial degree of -aromatic extraction from the having a boilingrange of from 218 F. to 416 F.

lfrom a high sulfur crude oil with varyingvquantitles of anhydrousliquid HF at a temperature of about 80 F.

feed stock. The method of determining the specie dispersion is describedin the article Quantitative Determination of Aromatic Hydrocarbons by aNew Method by A. V. Grosse and R. C. Wackher, published in theIndustrial and Engineering Chemistry Analytical Edition, volume 11, No.11 (November 15, 1939) pages 614 to 624 inclusive. As shownlby the datein Table II, the effect of aromatic removal is reflected in the highTABLE I Sulfur extraction of heavy naphtha 'Dooren Extract TreatingOctane No. CFR-M Run ce HF l of Sulfury Loyer Loss, I No. 28g whatliixr...vt.| wt. per. Wt.

i r pci-crut l wuts pcrccntl Clear lcc. 3cc. l l ma! o ss! a 41.9 48.954.2 I 5 i i) 0S l 79.0 17.3 1.74 41.0 50.0 57.4 wn e on als mi 1.8940.7 50.9 59.6 1:. '20o o 03 v2.0 l 15.2 2.18 40.7 52.1 62.1

l Based on S Analyses.

The above data show a substantially complete rel moval of sulfur fromheavy naphtha. Although the raflinate show a slightly lower elearoctanerating than the feed, better lead responses are obtained on thedesulfurized stocks. The low treat.-

ing losses reflect a substantially negligible extraction of aromaticsfrom the feed stock, l

The advantage of extracting non-viscous hydrocarbon oils of the typeherein-described with hydrogen fluoride alone over using a. mixture ofgreater removal of aromatics is also reflected in the antiknock ratingof the motor fuel. It will be noted that in Run 1 there was obtained alowering of the clear octane number of from 41.9 for the feed stockto35.6. whereas when hydrogen ing the dashed lower for the railinateobtained in the 4hydrogen nuoride and boron iluoride treatment than forthe raillnate obtained in th'e; extraction using hydrogen nuoride alone.

The present invention is not to be confused with prior art processes ot.treating petroleum stocks with liquid hydrogenA fluoride. wherein thehydrogen fluoride is employed as a treating agent in amounts and underconditions lwhich do not permit stratiilcation into a railinate fractionand an extract fraction. The process of the hereindescribed invention incontradistinction to' prior art processes provides a process whereby thesuliur-containing constituents `of the non-viscous hydrocarbon oils areextracted with a suincient quantity of anhydrous liquid hydrogenfluoride to permit stratication of a substantially sulfuri'ree raiiinateand a sulfur-containing extract, the solvent in both the ranlnate andthe extract being recovered and recycled for further extraction of thefeed stock.

In addition to the removal of sulfur4 from nonviscous hydrocarbon oils,extraction with' liquid anhydrous hydrogen uoride also effectivelyremoves nitrogen and/or oxygen compounds from such stocks.

The term non-viscous hydrocarbon oil" as used herein and in the appendedclaims means a hydrocarbon oil less viscous `than hydrocarbon oilswithin the lubricating oil range; namely,

those having a Saybolt Universal viscosity at 100 F. of less than about60 seconds.

It is to be understood that while certain preferred embodiments of theinvention have been herein-described. the invention; is not to belimited thereto, but includes within its scope such modifications asfairly come within the spirit of the appended claims.

Weclaim: i

1. The method of selectively desulfurizing a non-viscousaromatic-containing hydrocarbon oil comprising contacting said oil witha solvent consisting of liquid anhydrous hydrogen fluoride at atemperature within the range of about 300 F. to about 400 F., iiashingolT any hydrocarbon gases and hydrogen sulfide resulting from theconversion of sulfur compounds in said oil, coolmixture of hydrocarbonsand hydrogen iluoride to a temperature of from about F. to about 212 F.,contacting the cooled mixture with additional liquid anhydrous hydrogennuoride while maintaining a pressure suilicient to maintain the solventand hydrocarbon oil in the liquid phase, permitting the mixture of saidoil and liquid hydrogen fluoride to stratify into an aromatic-containingratllnate phase substantially free of sulfur and a sulfur-containingextract phase, separating said phases and removing the hydrogen nuoridefrom said phases.

2. The method of selectively desulfurizing a non-viscousaromatic-containinghydrocarbon oil comprising treating said oil withliquid anhydrous hydrogen fluoride at a temperature with- 8 in the rangeof about 300 flashing of! any hydrocarbon sulnde resulting from theconversion of sulfur compounds in said oil, cooling the ashed mixture toa temperature of from about 0 F. to about 212 F.. agitating said mixtureat said lower temseparate into an aromatic-containing railinate phasesubstantially free of sulfur and a sulfurcontaining extract phase andseparating said phases.

3. I'he method of non-viscous aromatic-containing hydrocarbon oii furcompounds in said oil, cooling the flashed mixture to a temperature ofabout 0 F. to about 212 F., permitting .the mixture to separate into toabout 400 F., cooling the mixture to a tem-v perature of from about 0 F..to about 212 F.. contacting the cooled mixture with additional liquidanhydrous hydrogen fluoride while maintaining a pressure sunlcient tomaintain the solvent and hydrocarbon oil in the liquid phase, permittingthe mixture of said oil and liquid hydrogen fluoride to stratify into anaromatic-containing raiiinate phase substantially free of silliur and asulfur-containing phase, separating said phases and removing thehydrogen nuoride from said phases.

BERNARD L. EVERING. ARTHUR P. LIEN. JAMES M. PAGE, Jn. REFERENCES CITEDThe following references are of record in the file of this patent:

UNITED STATES PATENTS 60 Number Name Date 2,282,451 Brooks May 12, 19422,320,629 Matuszak June 1, 1943 2,343,841 Burk Mar. 7, 1944 2,366,743Matuszak Jan. 9. 1945 65 2,371,341 Matuszak Mar. 13, 1945 2,375,675Matuszak May 8, 1945 2,378,762 Frey June 19, 1945

